Helmets are able to protect a wearer's head from impact through the deformation or even crushing of energy absorbing materials, such as foams. An important design consideration for helmets is the density of the energy absorbing material. A higher density material may absorb a harder impact but provide less cushioning, while lower density foam may provide a gentler cushion with the risk of “bottoming out” in a hard impact. Constructing an impact liner of a single density material may address one problem while creating another. Additionally, increasing the thickness of low-density materials to handle the harder impacts may increase the overall size of the helmet, potentially increasing the risk of rotational injuries.
Helmets may sometimes employ energy management materials of different densities to meet various needs, such as impact rating, as well as the overall size, shape, and weight of the helmet. Multi-density impact liners have previously been formed by incorporating preformed portions of material having one density, called pucks, into the body of an impact liner having a second density. However, conventional use of pucks requires them to “float” in the impact liner body, limiting the degree to which a high-density puck can reduce the thickness of a helmet. Additionally, floating pucks may reduce the overall structural soundness of a helmet, particularly where they interface with the foam of a different density.